Conventionally, there has been known a separate-type air conditioner in which a refrigerant circuit is configured by the interconnection of a heat source unit and a utilization unit via a refrigerant communication pipe. In such an air conditioner, the refrigerant may leak from the refrigerant circuit for some reasons. Such refrigerant leak causes deterioration of air conditioning performance and damages to constituent equipment. Therefore, it is preferable to provide a function to determine the adequacy of the refrigerant quantity charged in the air conditioner.
For such problems, a method has been proposed in which the adequacy of the refrigerant quantity is determined by using the degree of superheating of the refrigerant at an outlet of an outdoor heat exchanger during heating operation and the degree of superheating of the refrigerant at an outlet of an indoor heat exchanger during cooling operation (see Patent Document 1). Also, another method has been proposed in which the adequacy of the refrigerant quantity is determined by using the degree of subcooling at the outlet of the outdoor heat exchanger during cooling operation (see Patent Document 2).    Patent Document 1    Japanese Patent Application Publication No. H02-208469    Patent Document 2    Japanese Patent Application Publication No. 2000-304388